Bronze howitzer casting technology ca. 1790

[cannonmn]

Recently I inspected and photographed about a dozen early American bronze howitzers, 3 of 8 or 8.25-inch bore (two different models) , and the rest apparently 5.5 inch (3 different models.)  They ranged in date of casting from about 1775 to about 1800. 

One thing that really surprised me was that each and every one had a piece of iron extending from the face of the knob to the rear of the chamber, obviously cast in place.

The only thing I can think of was that perhaps these weapons were cast on cores and this piece of iron was the single core support, or chaplet, that was used.  I thought core casting had gone out in about 1760 in europe and that it was never really practiced to any extent in the US.

What's going on here?

Here's a slideshow with at least one of each of the different models, showing the core in outside and down-bore views.  The first couple of weapons are 8" at Fort Ticonderoga, and all the rest are 5.5-inch at Watervliet Arsenal, NY.

http://s17.photobucket.com/albums/b62/cannonmn/miscforumsetc/forums%2014/?action=view&current=a25119a6.pbw

[intoodeep]

Ok, Dumb Question Alert! What would keep that in place while firing?? 

[cannonmn]

Ok, Dumb Question Alert! What would keep that in place while firing?? 

If I had to guess, I'd guess they made the iron piece out of wrought iron, and put some contour on it such as re-rod, or course threading, hour-glass shape, whatever, so it could not move laterally once the bronze had cooled.  Some day we'll have to x-ray one to see what the profile is.

[dan610324]

of course its probably profiled

but they maybe also tinplated it , then its soldered also to the bronce after casting

I know that was used for other purposes in early castings